Paraquat Residues Research Articles

Herbizideinsatz und Mäuse in Forstkulturen

Application of herbizides and voles in forest plantations Two areas in different spruce plantations were treated with Gramoxone® (Paraquat). Changes of the density of small mammals especially of the Field Vole(Microtus agrestis) and the Common Vole(Microtus arvalis) were observed. Residues of Paraquat in the excretions of marked individuals in the treated area were not detected with few exception. The problem of debarking young trees by starving voles and food scarcity caused by the weedkiller is discussed.

Determination of paraquat residues in food crops by gas chromatography.

A method is described for determining paraquat residues in lettuce, carrots and onions. The procedure is based on the extraction of the sample with 5N H2SO4 and catalytic hydrogenation of the acid extract. This is followed by column cleanup on alumina and subsequent determination by gas chromatography. Recoveries of paraquat added to lettuce, carrots and onion at 0.5, 0.1, and 0.05 ppm were between 75 to 86%, with maximum standard error of 4%. The lower limit of this method is in the 0.05 ppm range.

Determination of diquat and paraquat residues in soil by gas chromatography.

Determination of diquat and paraquat residues in soil by gas chromatography.

Colorimetric Determination of Paraquat Residues in Soil and Water

Abstract A modified colorimetric method is presented for the determination of paraquat in agricultural arunoff samples. The soil extraction step of existing methods is shortened, making the method more suitable for routine analysis of large numbers of samples. Recoveries from spiked soil samples (0.5–5.0 ppm) and water samples (0.1–2.0 ppm) averaged 91-98 and 80-94%, respectively.

Some Ecological Effects of the Use of Paraquat for the Control of Weeds in Small Lakes

The use of pesticides in water has always been regarded with suspicion because of the special possibilities of dangers to man, domestic animals, irrigated crops, wildlife and aquatic organisms. In addition to possible direct toxicity, secondary hazards may arise from the disappearance from the aquatic ecosystem of the bulk of the primary producers, together with other effects arising from the decomposition of plant material. With the increasing interest in diquat and paraquat as aquatic herbicides a collaborative experiment was made in which the Monks Wood Experimental Station (Nature Conservancy), Jealotts Hill Research Station (I.C.I. Ltd), the Water Pollution Research Laboratory (Ministry of Technology) and the Botany Department of the University of Nottingham studied the results of applications of paraquat to a series of small lakes. Physico-chemical effects and response of captive fish are reported by Owens and Maris (in preparation), whilst biological effects and paraquat residue determinations are described here.

Grazing trials on paraquat‐treated pasture

AbstractCattle suffered no toxic effects over a four‐week period when turned loose on pasture immediately after it had been sprayed with paraquat at 1 lb/acre, and continued to graze the brown dried herbage as they would have grazed hay. It can be calculated that the animals were consuming approximately half their acute oral LD50 of paraquat every day, for the first two weeks at least, without showing any signs of toxic effects. This result, together with the low levels of paraquat detected in the urine of animals on sprayed pasture and high levels in the faeces indicates that when paraquat is administered as a residue on grass very little is available for absorption. No significant residues of paraquat could be detected in the carcass of an animal slaughtered three days after return to unsprayed pasture. Residues of 0.02 ppm paraquat were found in the milk of the two cows on the first day after spraying only, when initial residues on the herbage were just over 1000 ppm. Thereafter no residues were detected by a method capable of detecting 0.005 ppm.Horses showed definite ill effects, namely local lesions of the mouth and increased mucous secretions, after grazing the newly sprayed pasture. On return to normal pasture they quickly recovered, and a horse slaughtered 5 months later showed no post mortem abnormalities. Results of a further trial, in which the symptoms were much less marked, suggested that a short period of weathering of the pasture after spraying would reduce the harmful effects on horses.

Production and viability of eggs from hens treated with paraquat.

IN the communication from Dunachie and Fletcher1 it is shown that when paraquat is injected into fertile hen's eggs to give a final concentration greater than approximately 0.1 p.p.m. the subsequent rate of hatching was reduced. Because hens may eat food containing residues of paraquat from previous sprayings I made the following experiment to determine whether the amount of paraquat likely to be present would cause similar effects.